Backpack



FIG. 1 is a front perspective view of the backpack;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a right elevation view thereof;

FIG. 5 is a left elevation view thereof; and,

FIG. 6 is a top plan view thereof.

The broken lines shown in the drawings are for the purpose of illustrating elements of the backpack which form no part of the claimed design. The broken lines in the form of dot-dash lines define the bounds of the claimed design and form no part thereof. 

CLAIM The ornamental design for a backpack, as shown and described. 